Field of Invention
The present invention relates to a light emitting module. More particularly, the present invention relates to a beam collimated light emitting module with a light color mixed chamber.
Description of Related Art
Lighting devices are indispensable tools in our daily lives. Conventional lighting devices usually use light bulbs or lamps as the light sources. Fluorescent tubes, incandescent bulbs, and halogen light bulbs are most frequently used among these light bulbs or lamps but are not energy economic. Therefore, lighting devices including light-emitting diodes (LED) as light sources have become more and more popular in recent years. Compared with the incandescent bulbs, LED light sources have the advantages such as long lifespan, low energy consumption, good shock resistance, and high brightness. Moreover, LED light source may be manufactured by a blue light emitting chip covered by yellow phosphor powders. When the blue light emitting chip emits light, a blue light enters and excites the yellow phosphor powders, such that the center area of the LED light source with high-density chips is apt to emit a bluish white light, and the surrounding area of the LED light source with low-density chips tend to emit a yellowish white light. Such phenomenon is more obviously observed in the type of integrated packaging LEDs.
A conventional lighting device utilizing a LED as a light source, e.g., a flashlight, a streetlight, or a car lamp, may be composed of a light holder and a light source, and may optionally include a reflector or a lens. If the lighting device is composed of the light holder, the light source, and the reflector, although the light of the light source can be reflected by the reflector to improve the beam collimation of the lighting device, the phenomenon for the center area of the LED light source emitting the bluish white light and the surrounding area of the LED light source emitting the yellowish white light still exists and reduces the uniformity of the light color. Furthermore, If the lighting device is composed of the light holder, the light source, and the lens, although the micro structure of the lens can be used to scatter the central bluish white light and the surrounding yellowish white light to improve the uniformity of the light color, the light of the lighting device is therefore diverged due to the scattering of the light. As a result, the beam collimation of the lighting device may be degraded.
It is difficult to simultaneously improve the uniformity of the light color and the beam collimation for the conventional lighting device. As such, the optical performance of the lighting device is limited and the consumers' requirement is unsatisfied.